This is the presentation about landsliding that I give almost three years ago at the IWL conference in Naples.

1. Analysis of Saturated and Unsaturated Landslide
Triggering through the Distributed Hydrological
Model GEOtop
Riccardo Rigon, Silvia Simoni, Cristiano Lanni, Giuseppe Formetta
First Italian Workshop on Landslides - Napoli 8-11 June, 2008
Monday, June 25, 12

2. Landslide an approach by GEOtop
... you know what I'm craving?
A little perspective. That's it. ...
Anton Egò
What’s for
•We tried to to have a model that could approach consistently the modeling of
water fluxes and head in a hillslope.
•To get landslide triggering ... well, and other processes.
•To be able to interpret field measures.
•And to cope the model with remote sensed data.
2
R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. Tarantino
Monday, June 25, 12

3. Landslide an approach by GEOtop
This is it !
snow, ice,
permafrost
water
cycle
shallow
landslides
3
R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. Tarantino
Monday, June 25, 12

4. Landslide an approach by GEOtop
The GEOtop project
1. GEOtop is a distributed hydrological model, which integrates water and
energy budget in complex terrain [Rigon et al. 2006].
2. It performs energy balance and water balance, computing energy fluxes
between soil and atmosphere, subsurface and surface flows [ Bertoldi et al.,
2006].
Rigon et al., JHM, 2006, Bertoldi et al., JHM, 2006, Simoni, 2007, Endrizzi, 2007
http://www.geotop.org 4
R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. Tarantino
Monday, June 25, 12

5. Landslide an approach by GEOtop
The GEOtop project
Slope stability is assessed through the probabilistic and
dynamic module GEOtop-FS [Simoni et al, 2007].
GEOtop 2010
I/O Data Subsurface Surface
Assimilation Flows Flows
Energy Snow
Vegetation Radiation
Budget &
Cryosphere
5
R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. Tarantino
Monday, June 25, 12

6. Landslide an approach by GEOtop
The Basic, however, is the dynamics of
the soil water column
Mass Volume
Air gas
Mag Vag
Frozen water
Mi Vi
Ms Vs
Liquid water
Mlw Vlw
Soil particles
Msp Vsp
6
R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. Tarantino
Monday, June 25, 12

7. Landslide an approach by GEOtop
Mass Budget of Condensed Water
⇤t (⇥lw lw
⌃ ⌃
+ ⇥i i ) + ⇤ · (⇥lw Jlw + ⇥i Ji ) ⇥lw slw ⇥i si = 0
The equation does not come alone. It fulfills some
constraints:
r lw ⇥se
or
r lw + i ⇥s
7
R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. Tarantino
Monday, June 25, 12

8. Landslide an approach by GEOtop
Mass Budget of Condensed Water
Some simplifications are readily made:
- The flux of ice is negligible, i.e. ⇥
Ji 0
- The source/sink of ice is also neglibile, i.e. si 0
Thus the equation reduces to
⇧t (⇥lw min(⇤se , max( r , lw )) + ⇥i min(max(0, i ), ⇤s ) + ⇤ · (⇥lw Jlw ) ⇥lw slw = 0
8
R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. Tarantino
Monday, June 25, 12

9. Landslide an approach by GEOtop
Mass Budget of Condensed Water
If the ice is neglected, for the present case, the conventional
Richard’s equation is obtained
⇧t (⇥lw min(⇤se , max( r , lw ))) + ⇤ · (⇥lw Jlw ) ⇥lw slw = 0
True: we also have to parametrize soil water retention curves and
hydraulic conductivity [L T-1] (please do not call permeability [L2]).
For the first we use the van Genucthen (1980) scheme for the
second Mualem (1976)
9
R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. Tarantino
Monday, June 25, 12

10. Landslide an approach by GEOtop
A Flash back ...
into the geological/gemorphological community
Two main contenders debated in the last decade about
modeling shallow landslides. Just to personalize this, as it is
common nowadays
The West Coast guys The USGSes 10
R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. Tarantino
Monday, June 25, 12

11. Landslide an approach by GEOtop
A Flash back ...
into the geological/gemorphological community
Bill and Dave assert that shallow landslides can be approximately
explained by saturation excess hydrology, lateral flow, and
infinity slope stability. They produced the widely used and cited
SHALSTAB model.
Montgomery and Dietrich, 1994
11
R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. Tarantino
Monday, June 25, 12

12. Landslide an approach by GEOtop
A Flash back ...
into the geological/gemorphological community
Dick Iverson (S. Baum, J. Godt) insists that the transient vertical
effects counts in building a sufficient pore pressure to destabilize
hillslope. This broughto TRIGRS
Iverson, 2000; Baum et al., 2002
12
R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. Tarantino
Monday, June 25, 12

13. Landslide an approach by GEOtop
A Flash back ...
with intrusion of hydrologists
One Italian gang tried to reconcile the fighters observing that all
of that above derives from the Richards equation with various
degree of simplifications, and proposed a linear simplified
theory with analytical solutions available that superimpose the
SHALSTAB theory with Iverson’s one, to be convoluted to
precipitations.
D’Odorico et al., WRR, 2005; Cordano and Rigon, WRR, 2008 13
R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. Tarantino
Monday, June 25, 12

14. Landslide an approach by GEOtop
A Flash back ...
with intrusion of hydrologists
I.M.H.O., the linear theory works close to saturation but has some
problems of parameter characterizations in more unsaturated
cases, which caused some headaches to us.
To make a long story short, we did our best with simplified
theories*, but finally we had to observe that going directly to a
numerical non linear model was the right and conceptually
simpler choice.
*I am pretty sure that Frattini and Crosta, 2009 does it better
14
R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. Tarantino
Monday, June 25, 12

15. Landslide an approach by GEOtop
A case study
Rio Corda, Italy, Trentino
•Area: 13.4 km2
•Min elevation: 924 m
•Max elevation: 2890 m
•Two main ephemeral stream
•No steep, but hilly Oregon: an
Alpine small catchment
15
R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. Tarantino
Monday, June 25, 12

16. Landslide an approach by GEOtop
A case study
Rio Corda, Italy, Trentino
A landslide happened in June 2008 and we tried to reproduce that
event
16
R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. Tarantino
Monday, June 25, 12

17. Landslide an approach by GEOtop
A case study
Rio Corda, Italy, Trentino
We investigated the water pressures in the yellow point.
17
R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. Tarantino
Monday, June 25, 12

18. Landslide an approach by GEOtop
A case study
Rio Corda, Italy, Trentino
A landslide happened in June 2008 and we tried to reproduce that Psi @ point 1
event
15
0.025 m
0.1 m
0.25 m
0.5 m
0.825 m
1.2 m
water suction [mm]
1000
10
rain [mm/h]
0
-1000
5
-2500
0
30/04 03/05 06/05 09/05 12/05 15/05 18/05 21/05 24/05 27/05 30/05 02/06 05/06 08/06 11/06
time (days/month)
18
R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. Tarantino
Monday, June 25, 12

19. Landslide an approach by GEOtop
A case study
Rio Corda, Italy, Trentino
A landslide happened in June 2008 and we tried to reproduce that Psi @ point 1
event
15
0.025 m
0.1 m
0.25 m
0.5 m
0.825 m
1.2 m
water suction [mm]
1000
10
rain [mm/h]
0
-1000
5
-2500
0
30/04 03/05 06/05 09/05 12/05 15/05 18/05 21/05 24/05 27/05 30/05 02/06 05/06 08/06 11/06
time (days/month)
18
R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. Tarantino
Monday, June 25, 12

20. Landslide an approach by GEOtop
A case study
Rio Corda, Italy, Trentino
A landslide happened in June 2008 and we tried to reproduce that Psi @ point 1
event
15
0.025 m
0.1 m
0.25 m
0.5 m
0.825 m
1.2 m
water suction [mm]
1000
10
rain [mm/h]
0
-1000
5
-2500
0
30/04 03/05 06/05 09/05 12/05 15/05 18/05 21/05 24/05 27/05 30/05 02/06 05/06 08/06 11/06
time (days/month)
15.05.08 18
R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. Tarantino
Monday, June 25, 12

21. Landslide an approach by GEOtop
A case study
Rio Corda, Italy, Trentino
A landslide happened in June 2008 and we tried to reproduce that Psi @ point 1
event
15
0.025 m
0.1 m
0.25 m
0.5 m
0.825 m
1.2 m
water suction [mm]
1000
10
rain [mm/h]
0
-1000
5
-2500
0
30/04 03/05 06/05 09/05 12/05 15/05 18/05 21/05 24/05 27/05 30/05 02/06 05/06 08/06 11/06
time (days/month)
15.05.08 18
R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. Tarantino
Monday, June 25, 12

22. Landslide an approach by GEOtop
A case study
Rio Corda, Italy, Trentino
A landslide happened in June 2008 and we tried to reproduce that Psi @ point 1
event
15
0.025 m
0.1 m
0.25 m
0.5 m
0.825 m
1.2 m
water suction [mm]
1000
10
rain [mm/h]
0
-1000
5
-2500
0
30/04 03/05 06/05 09/05 12/05 15/05 18/05 21/05 24/05 27/05 30/05 02/06 05/06 08/06 11/06
time (days/month)
15.05.08 22.05.08
18
R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. Tarantino
Monday, June 25, 12

23. Landslide an approach by GEOtop
A case study
Rio Corda, Italy, Trentino
We investigated the water pressures in the yellow point.
Psi point 1
15
0.025 m
0.1 m
0.25 m
0.5 m
0.825 m
1500
1.2 m
10
water suction [mm]
rain [mm/h]
500
−500
5
−1500
−2500
0
30/04 05/05 10/05 15/05 20/05 25/05 30/05
time (days/month)
19
R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. Tarantino
Monday, June 25, 12

24. Landslide an approach by GEOtop
A case study
Rio Corda, Italy, Trentino
Method in Simoni et al., HP, 2008 20
R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. Tarantino
Monday, June 25, 12

25. Landslide an approach by GEOtop
A case study
Rio Corda, Italy, Trentino
Method in Simoni et al., HP, 2008 20
R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. Tarantino
Monday, June 25, 12

26. Landslide an approach by GEOtop
A simple comparison between GEOtop and SHALSTAB
Rio Corda, Italy, Trentino
21
R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. Tarantino
Monday, June 25, 12

27. Landslide an approach by GEOtop
A simple comparison between GEOtop and SHALSTAB
Rio Corda, Italy, Trentino
22
R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. Tarantino
Monday, June 25, 12

28. Landslide an approach by GEOtop
A simple comparison between GEOtop and SHALSTAB
Rio Corda, Italy, Trentino
Top Index - Saturated Top Index - Not saturated
GEOtop -Saturated 26.9 15.04
GEOtop Not Saturated 15.04 43.02
23
R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. Tarantino
Monday, June 25, 12

29. Landslide an approach by GEOtop
A simple comparison between GEOtop and SHALSTAB
Rio Corda, Italy, Trentino
24
R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. Tarantino
Monday, June 25, 12

30. Landslide an approach by GEOtop
Conjectures on the differences
Rio Corda, Italy, Trentino
Differences are due to:
•Non stationarity of the response
•Downslope reinfiltration of surface water
•The treatment of surface water in GEOtop that set a boundary conditions for
the water table elevation at the channel network
This is apparent, for instance, after Cordano and Rigon, 2008.
25
R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. Tarantino
Monday, June 25, 12

31. Landslide an approach by GEOtop
A theoretical investigation to assess these behavior
The aim is to investigate the role of some factors that control the processes
of pore-water pressure redistribution and, hence, the factor of safety (FS) of
the slope.
 Geometry
 Soil Type
 Antecedent Soil Moisture Conditions
 Rainfall intensities and volumes
Different Values of these features are chosen as described below
26
R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. Tarantino
Monday, June 25, 12

32. Landslide an approach by GEOtop
A theoretical investigation to assess these behavior
Lanni et al., 2009, in preparation 27
R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. Tarantino
Monday, June 25, 12

33. Landslide an approach by GEOtop
A theoretical investigation to assess these behavior
Lanni et al., 2009, in preparation 27
R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. Tarantino
Monday, June 25, 12

34. Landslide an approach by GEOtop
Boundary Conditions
 On the sides  On the sides
AB, BC, CD, DE AF, EF (switch of the b.c.)
Omogeneous Neumann Boundary Neumann or Dirichlet Boundary Conditions,
Conditions depending from moisture conditions at the
28
first soil layer
R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. Tarantino
Monday, June 25, 12

35. Landslide an approach by GEOtop
Computer Experiment Set-up
 Two cases analyzed: steep and gentle slope
i. STEEP SLOPE, when the angle of tan φ '
the slope is bigger than the = 0.7
frictional angle of the soil tan α1
ii. GENTLE SLOPE, when the angle
of the slope is smaller (or is the tan φ '
same) than the frictional angle = 1.0
€ tan α 2
of the soil 29
R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. Tarantino
Monday, June 25, 12

36. Landslide an approach by GEOtop
The Computer Experiment Set-up
 Two cases analyzed: sandy soil and sandy-silt soil
SANDY SOIL % sand = 80
S1
% silt = 20
o
φ '= 35
−4
K sat = 10 m /s
€
€ % sand = 40
SANDY-SILT SOIL
€ % silt = 60
S2 o
€ φ '= 30
K sat = 10−6 m /s
€
€
Through physical properties and soil texture it is possible to
€
get the shape parameters of the van Genuchten model using
Vereecken PTF€ (1989)
30
R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. Tarantino
Monday, June 25, 12

37. Landslide an approach by GEOtop
The Computer Experiment Set-up
Initial Conditions
ψ (z) = ψ bottom + γ w ⋅ ( H − z)
€
Chosen so as to obtain the following values of initial safety factor of the slope:
FS=1.05 for CI1 initial condition
FS=1.10 for CI2 initial condition
FS=1.20 for CI3 initial condition 31
R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. Tarantino
Monday, June 25, 12

38. Landslide an approach by GEOtop
The Computer Experiment Set-up
The above prescriptions turn into:
0.45 0.55
tan φ ' (γ wψ ) (γ wψ b )
FS = + tan φ '
tan α γ ⋅ h ⋅ sin α ⋅ cos α
€ 0.35 (steep) 0.05 (gentle) for CI1
0.7 if steep slope case
0.40 (steep) 0.10 (gentle) for CI2
1.0 if gentle slope case
0.50 (steep) 0.20 (gentle) for CI3
32
R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. Tarantino
Monday, June 25, 12

39. Landslide an approach by GEOtop
The Computer Experiment Set-up
 In unsaturated medium the total stress is defined as:
σ = (σ − ua ) + χ (ψ )( ua − uw ) Bishop (1959)
χ valued according to Khalili & Kabbaz empirical relation (1998)
€ ⎡ u − u ⎤−0.55
χ = ⎢ a w ⎥ if ( ua − uw ) b < ( ua − uw ) b
⎣( ua − uw ) b ⎦
χ =1 if ( ua − uw ) b ≥ ( ua − uw ) b
where:€ (ua − uw ) b [ FL−2 ]
€ €
is the air-entry value matrix suction
33
€
R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. Tarantino
Monday, June 25, 12

40. Landslide an approach by GEOtop
Some Results
work in progress
Soil Type Slope Initial Conditions Rainfall Duration Behavior
Coarse Steep Wet Short 1D
Coarse Steep Wet Long 1D
Coarse Steep Dry Long 2D
· · · · ·
Fine Gentle Wet Any 1D
1D means that soil failure happens above the bedrock
2D means that soil failure happens at the bedrock
Probably this also affect the position in the hillside where the failure
can happen.
34
R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. Tarantino
Monday, June 25, 12

41. Landslide an approach by GEOtop
Some Further Results Results
work in progress by I. Pretto and C. Lanni
35
R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. Tarantino
Monday, June 25, 12

42. Landslide an approach by GEOtop
Some Further Results Results
work in progress by I. Pretto and C. Lanni
In real life the water table has a curvature due to the channal drainage
36
R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. Tarantino
Monday, June 25, 12

43. Landslide an approach by GEOtop
Beyond GEOtop: The complete GEOFRAME framework
Eclipse RCP
uDig
PostGIS JGrass
Postgres
J-Console Engine GIS engine
OpenMI
Web
The Horton
services UIBuilder
Machine
WMS Models
WFS-T H2 spatial
WPS
GRASS
BeeGIS
www.slideshare.net/GEOFRAMEcafe/geoframe-a-system-for-doing-hydrology-by-computer
37
R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. Tarantino
Monday, June 25, 12

44. Landslide an approach by GEOtop
First Steps into GEOFRAME: First Componentization
Next year
Meteo Energy Water
I/O + +
Forcings Budget Budget
The first version
38
R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. Tarantino
Monday, June 25, 12

45. Landslide an approach by GEOtop
First Steps into GEOFRAME: Second Componentization
Next year
Meteo Energy Water
I/O
Forcings Budget Budget
The second version
39
R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. Tarantino
Monday, June 25, 12

46. Landslide an approach by GEOtop
Further splitting will follows
I/O Data Subsurface Surface
Assimilation Flows Flows
Energy Snow
Vegetation Radiation &
Budget
Cryosphere
40
R. Rigon, S. Simoni, C. Lanni, G. Formetta and A. Tarantino
Monday, June 25, 12

47. Hoping that Bill, Dick Dave, forgive me!
Thank you for your attention
Free GIS: www.jgrass.org
Free Hydrological Model: www.geotop.org
Search also GEOFRAME Cafe on Slideshare
Monday, June 25, 12